1. Field of the Invention
The present invention relates to alcohol testing devices and specifically to a device which uses the results of a sobriety breath test to control a switch in an automobile ignition system or in other machinery.
2. Description of the Prior Art
Automobile driving by intoxicated persons is a serious problem responsible for thousands of accidental deaths and extensive property damage every year, yet despite various preventive efforts the problem has defied solution. Many schemes have been suggested to prevent drunks from driving, but because the schemes have all involved some driver inconvenience, none has gained widespread acceptance. Alcohol intoxication can be detected in various ways, all suffering from some drawback. A practical preventive test must be executed automatically without supervision.
Reaction time and dexterity test results such as disclosed in U.S. Pat. Nos. 3,665,447 and 3,610,943 respectively depend on individual abilities, are only indirectly related to degree of intoxication, and are not always meaningful. Alcohol intoxication is directly measured in a driver's breath by U.S. Pat. No. 3,186,508 by measuring the optical property change of a chemical solution which is bleached by reacting with alcohol fumes. This system requires an inconvenient frequent change of the solution. U.S. Pat. No. 3,823,382 tests intoxication directly by an exothermic reaction of chemical granules with alcohol in a breath sample with a mercury thermostat to measure the amount of heat generated. The thermostat must be replaced after a failed test. U.S. Pat. No. 4,093,945, tests intoxication by oxidizing any alcohol in a breath sample and measures the heat given off by a change in the electrical resistance of a sensor. That system is relatively complex and expensive.
In short, prior art drunk-driving prevention devices generally can be evaded, are inaccurate, unreliable, tedious, inconvenient, or complex and prohibitively expensive. For these and other reasons, no drunk-driving prevention system has gained wide-spread acceptance. There remains, therefore, a real need for a convenient, reliable, and inexpensive sobriety interlock system.